Macfarlane, D.F. 1980 Engineering geology of the Ball Hut Road, Mount Cook National Park. Lower Hutt: New Zealand Geological Survey. New Zealand Geological Survey report EG 333 25 p.
Abstract: The Ball Hut road provides vehicular access to the upper Tasman Valley along the western edge of the Tasman Glacier. From Blue Lakes to the old Ball Hut site at the confluence of the Ball and Tasman Glaciers the road is constructed within a narrow paraglacial valley formed between the lateral moraine of the glacier and the in situ bedrock forming the Mount Cook Range. Due to its location wthin a highly active alpine environment the road is subjected to extreme runoff and erosion, debris deposition (including avalanche) and slumping due to failure of the moraine wall which occurs as a result of high intensity (storm) rainfall although the spring thaw contributes to slump failures. The road was closed following a major storm in May 1978 but subsequently reinstates as far as Husky Flat following repair work to areas affected by erosion. Due to progressive slump failure the section of road from Husky Flat to the old Ball Hut site was abandoned. Another major storm early in December 1979 occurred four weeks after the re-opening of the road and resulted in its closure once again. An analytical assessment of the engineering geological factors affecting the stability of the road indicates that restoration of access to Husky Flat is possible at reasonable expense although the long term stability of this section of the road cannot be guaranteed. The road beyond Husky Flat is too unstable for restoration to be considered.